Proper Oil for stock 4.0L xj

[techno1154]

I typically use Amsoil AMO which is a full syn extended life 10w-40 oil with high levels of ZDDP.

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I too am using Amsoil in the 20-50 flavor since the 4.0L was at 135,000 miles. It is now at 275,000 miles and still read 60 PSI running and 40 PSI hot at idle. My oil changes are at 20,000+/- miles with an oil filter change every 10,000 miles at which time I use about 1 quart to top it up. And as Johnnie Walker said, Amsoil do have plenty of ZDDP.

The bet oil to use? Well, as indicated, it could be almost impossible to get a consensus on the subject.